1. Technical Field
The present invention is directed toward nebulizers for medicating a patient's lungs and, more particularly, to a continuous flow adaptor for a nebulizer.
2. Background Art
Nebulizers are devices for delivering atomized medication to air to be inhaled into the lungs of a patient. A variety of nebulizer structures are known in the medical field. An exemplary nebulizer is that disclosed in Farr, U.S. Pat. No. 4,566,452. Farr discloses a nebulizer having a nebulizer top and reservoir bottom which are threadably connectable. A gas jet extends from the reservoir bottom along a longitudinal axis of the reservoir bottom. A liquid spray nozzle surrounds the gas jet defining a passageway for liquid between the gas jet and the liquid nozzle. At the top of the gas jet is a gas orifice which leads into a space in fluid communication with the liquid nozzle passageway. A liquid orifice in a top of the liquid nozzle is axially aligned with the orifice in the gas jet. A diffuser is connected to the nebulizer top and spaced from the nozzle orifice with the nebulizer top and reservoir bottom threadably connected. As gas is caused to flow through the gas jet, a vacuum is formed in the space between the gas orifice and the nozzle orifice, drawing fluid for nebulization to the fluid nozzle orifice. Nebulized fluid impinges upon the diffuser, causing oversized droplets to stick to the diffuser and providing a finely nebulized mist for delivery to the lungs of a patient.
Nebulizers are often installed in an inhalation circuit of a mechanical ventilator. The ventilator augments respiration of a patient unable to sustain breathing on his own and the nebulizer provides medication applied to the patient's lungs. Nebulizers such as that disclosed in Farr typically have a select volume defined by the size of the reservoir. One problem with such a structure occurs when a patient requires delivery of a volume of nebulized medication in excess of the select volume of the nebulizer reservoir. Using a structure such as that disclosed in Farr typically requires that the reservoir top be detached from the reservoir bottom and additional medication poured into the reservoir. However, this procedure results in depressurizing and a complete loss of function of the ventilator system until the nebulizer top is reattached. In addition, there is a possibility of cross-contamination into and out of the reservoir system. Furthermore, when the nebulizer top is removed from the reservoir bottom, nebulization cannot take place and, therefore, medication cannot reach the patient's lungs. In some cases, particularly with critical care patients, these problems can result in adverse affect upon the patient's treatment. Thus, a structure for allowing continuous refill of the nebulizer reservoir without disconnecting the nebulizer from the inhalation circuit is necessary.
One method of continuously supplying medication to a nebulizer reservoir has been to insert an IV needle through the side of the nebulizer reservoir. This method creates the potential for fluid leaks and introduction of particulate matter into the reservoir, which can result in clogging of the fluid nozzle. In addition, the needle hole presents an avenue for contamination.
A second method which has been used to continuously nebulize a patient is to attach a valve T-piece to the aerosol outlet prior to attaching the nebulizer to the inhalation circuit. Medication may then be introduced through the T-valve into the nebulizer reservoir. This procedure has the serious drawback of lowering the efficiency of the device by passing the added medication through the aerosol stream, resulting in coalescing of aerosol particles into the medication droplets and thereby reducing aerosol output and altering the mean particle size and distribution.
It is also known in the art to provide a liquid inlet in the side wall of nebulizer reservoir. Such an inlet is disclosed in Kremer, U.S. Pat. No. 4,456,179; Robert, U.S. Pat. No. 5,119,807; and Poole, Jr., U.S. Pat. No. 4,953,547. While such structures do allow for continuous feed of medication to a nebulizer reservoir, they are not without serious drawbacks. Most significantly, including such an inlet on every nebulizer increases the cost of manufacturing the nebulizer. Not only is the mold more complicated, but an additional manufacturing step is required to cap the inlet. Thus, nebulizer cost is increased even when the nebulizer will not be required to accommodate continuous feeding of medication. While hospitals could stock nebulizers with or without the reservoir inlet, this would increase shelf space requirements and inventory costs. In addition, the liquid inlet increases the bulk of the nebulizer, therefore making the nebulizers more difficult to package compactly and increasing the shelf space required to store the nebulizers. Particularly in this age of extreme sensitivity in the rising costs of health care, these prior art devices simply do not provide the flexibility necessary to efficiently address the full range of nebulizer requirements.
The continuous flow adaptor disclosed and claimed herein is directed toward overcoming one or more of the problems discussed above.